GI Hormones & Physiology

Question 1

What do gastric parietal cells produce?

Answer 1

HCl, intrinsic factor

Question 2

What do chief cells produce?

Answer 2

Pepsinogen

Question 3

What do G cells produce?

Answer 3

Gastrin

Question 4

What do mucous neck cells produce?

Answer 4

Bicarbonate mucus

Question 5

What is pepsin?

Answer 5

Proteolytic enzyme that hydrolyzes peptide bonds

Question 6

What is intrinsic factor?

Answer 6

Protein secreted by the parietal cells that combines with vitamin B12 and enables absorption in the terminal ileum

Question 7

What 3 substances stimulate HCl release by parietal cells?

Answer 7

1. Histamine
2. Acetylcholine
3. Gastrin

Question 8

What is the enterohepatic circulation?

Answer 8

Circulation of bile acids from the liver to the gut and back to the liver via the portal vein

Question 9

Where are most of the bile acids absorbed?

Answer 9

Terminal ileum

Question 10

How many times is the entire bile acid pool circulated during a typical meal?

Answer 10

Twice

Question 11

What are the stimulators of gallbladder emptying?

Answer 11

Cholecystokinin, vagal input

Question 12

What are the inhibitors of gallbladder emptying?

Answer 12

Somatostatin, sympathetics, vasoactive intestinal peptide (VIP)

Question 13

What is the source of cholecystokinin?

Answer 13

Duodenal mucosal cells

Question 14

What stimulates the release of cholecystokinin?

Answer 14

Fat, protein, amino acids, HCl

Question 15

What inhibits the release of cholecystokinin?

Answer 15

Trypsin, chymotrypsin

Question 16

What are the actions of cholecystokinin?

Answer 16

1. Empties gallbladder
2. Opens ampulla of Vater
3. Slows gastric emptying
4. Stimulates pancreatic acinar cell growth and release of exocrine products

Question 17

What is the source of secretin?

Answer 17

Duodenal cells (argyrophilic S cells)

Question 18

What stimulates the release of secretin?

Answer 18

pH < 4.5, fat in the duodenum

Question 19

What inhibits the release of secretin?

Answer 19

High pH in duodenum

Question 20

What are the actions of secretin?

Answer 20

1. Releases pancreatic bicarbonate, enzymes, and water
2. Releases bile and bicarbonate
3. Decreases LES tone
4. Decreases release of gastric acid

Question 21

What is the source of gastrin?

Answer 21

G cells

Question 22

What stimulates the release of gastrin?

Answer 22

1. Stomach peptides and amino acids
2. Vagal input
3. Calcium

Question 23

What inhibits the release of gastrin?

Answer 23

pH < 3.0, stomatostatin

Question 24

What are the actions of gastrin?

Answer 24

Release of HCl from parietal cells; trophic effects on mucosa of the stomach and small intestine

Question 25

What is the source of somatostatin?

Answer 25

Pancreatic D cells

Question 26

What stimulates the release of somatostatin?

Answer 26

Food

Question 27

What are the actions of somatostatin?

Answer 27

Globally inhibits GI function

Question 28

What is the purpose of the colon?

Answer 28

Reabsorption of water and storage of stool

Question 29

What is the main small bowel nutritional source?

Answer 29

Glutamine

Question 30

What is the main nutritional source of the colon?

Answer 30

Butyrate (SCFA)

Question 31

Where is calcium absorbed in the GI tract?

Answer 31

Duodenum actively, jejunum passively

Question 32

Where is iron absorbed in the GI tract?

Answer 32

Duodenum

Question 33

Which hormone primarily controls gallbladder contraction?

Answer 33

CCK

Question 34

What supplement does a patient need after removal of the terminal ileum or stomach?

Answer 34

Vitamin B12

Question 35

What are the main constituents of bile?

Answer 35

Water, phospholipids, bile acids, cholesterol, bilirubin

Question 36

What are most gallstones made of?

Answer 36

Cholesterol

Question 37

How do opiates affect the bowel?

Answer 37

By stimulating sodium absorption and inhibiting secretion in the ileum as well as decreasing GI motility by incoordinated peristalsis (therefore, place patients on stool softeners)

Question 38

Which electrolytes does the colon actively absorb?

Answer 38

Na, Cl

Question 39

Which electrolytes does the colon actively secrete?

Answer 39

Bicarbonate (plays a role in diarrhea causing the patient to have a normal anion gap acidosis)

Question 40

Which electrolytes does the colon passively secrete?

Answer 40

K

Question 41

What is the gastrocolic reflex?

Answer 41

Increased secretory and motor functions of the stomach result in increased colonic motility

Question 42

What is the blood supply to the liver?

Answer 42

75% from portal vein | 25% from hepatic artery

Question 43

What are Peyer patches?

Answer 43

Nodules of lymphoid tissue with B and T cells in the small intestine that selectively sample luminal antigens found in the terminal ileum